Many ink-jet printers, film recorders, and lithographic marking systems are amenable to produce integral images.
FIG. 1 shows an exemplary integral image 100 composed of a number of distinct sub-images which have been rendered upon an integral image substrate. See, e.g., Takanori Okoshi, “Three-Dimensional Imaging Techniques,” pg. 128, Academic Press, 1976, herein incorporated by reference. The integral image 100 may be formed of a “fly-eye” lens sheet 110 having a plurality of lens 115 placed over a sheet 120 having the sub-images. Each sub-image may have its own lens 115 for viewing.
Depending on the viewing angle, the observer may see a different sampling of sub-images of the sheet 110 appearing from different optical focusing positions. The resulting effects may include, for instance, lenticular imaging capabilities, such as image motion, zoom/magnification, flip, and three-dimensional (3-D) effects. As a result, position-dependent changes in appearance may occur along one or more directions of motion, and hologram capability can be supported.
FIG. 2 shows a magnified portion 220 of another exemplary integral image 200 having a number of small sub-images 212. The magnified portion 220 more clearly shows the small sub-images 212 arranged in a “checkerboard” pattern. In this arrangement, each sub-image 212 is surrounded with four (white) background image areas 214. These blank areas 214 are immediately above, below, left and right of each sub-image 212.
The white background areas 214 facilitate optical isolation of the sub-images 212. This may allow a lens to resolve each sub-image 212. In this example, each sub-image 210 may itself be a 600×600 dot-per-inch (dpi) pixel.
A problem, though, with electronic integral images is that they are not readily compressible by typical electronic data compression schemes. This is because many production printing systems employ lossy block-based compressions schemes that prohibit the accurate transmission of integral images into the print engine. Block-based compression schemes may include, for example, variations of the immensely popular JPEG (Joint Photographic Experts Group) compression standard: ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 1 (ISO/IEC JTC 1/SC 29/WG 1)—entitled “Coding of still pictures.” These compression techniques, however, will discard (or severely reduce) high-frequency spatial frequency information. For instance, for the integral image 200 shown in FIG. 2, compression processing will be concentrated into the checkerboard pattern, which is a pattern exhibiting uncommonly high frequency content. These high frequencies are assigned the fewest bits, and suffer the highest compression related loss.
Thus, integral images are uniquely disadvantaged by typical production system image paths, where severe signal losses may occur.